Marine conductor pipe



March 17, 1970 J, w TK s ETAL 3,500,904

MARINE CONDUCTOR PIPE Filed Dec. 15, 1967 2 Sheets-Sheet 1 INVENTORS:

BRUCE J. WATKINS WILLIAM W- GREENTREE THEIR AGENT qwrw March 17, 1970 B. J. WATKINS ETAL MARINE CONDUCTOR PIPE 2 Sheets-Sheet 2 Filed Dec. 15, 196'? INVENTORS:

BRUCE J- WATKINS WILLIAM W. GREENTREE THEIR AGENT United States Patent O 3,500,904 MARINE CONDUCTOR PIPE Bruce J. Watkins, San Pedro, Calif., and William W.

Greentree, Victoria, British Columbia, Canada, assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Dec. 15, 1967, Ser. No. 690,996 Int. Cl. E21b 33/035; F161 35/00 US. Cl. 166-.5 8 Claims ABSTRACT OF THE DISCLOSURE A marine conductor pipe for establishing communication with an underwater well wherein the conductor pipe is made up of a plurality of interconnecting pipe lengths each containing tubing string sections that mate when the pipe lengths are connected so that a composite marine conductor pipe is formed having longitudinal tubing strings extending therethrough. The lower end of the conductor is provided with coupling means for connecting the tubing strings to fluid passageways in the wellhead that communicate with the well.

BACKGROUND OF THE INVENTION In the quest to locate new oil deposits an increasing amount of offshore drilling and well completion is being conducted. Although the well casing and interior tubing strings of an offshore well may be extended to the water surface and closed off in a conventional manner such as is used on land wells, this arrangement is subject to damage and presents a navigational hazard for surface vessels. Accordingly, it is becoming increasingly popular to complete an offshore well entirely underwater, preferably with a production wellhead assembly located at or near the floor of a body of water. In order to perform certain completion and work-over operations on the well, it is necessary to establish communication between a surface platform or vessel and the well so that these operations can be performed. This is normally accomplished by extending a large-diameter pipe, commonly known as a marine conductor pipe, from the surface vessel down to the production wellhead. Subsequently, a tubing string is run down the marine conductor pipe and stabbed into a fitting on the production wellhead so that it is placed in communication with a tubing string extending into the well. In the event two or more tubing strings are employed in the well in side-by-side relationship, it thus becomes necessary to run these tubing strings down the marine conductor pipe and align and stab the marine conductor pipe tubing strings into the production wellhead to establish communication with the corresponding strings in the well. However, this is a particularly time-consuming and difficult operation since there is no guarantee that the tubing string or for that matter the marine conductor pipe remain perfectly straight so that aligning and stabbing the tubing strings becomes an especially difficult if not impossible operation. The tubing strings may, for example, become twisted during lowering so that they spiral one about the other.

In addition, time is of the essence in installing a marine conductor pipe since the labor costs, rental of the vessel 3,500,904 Patented Mar. 17, 1970 and down time of the well amount to thousands of dollars a day. Thus, ease of assembly of the conductor pipe and installation are critical factors in performing completion and maintenance operations on an underwater well. The problem is particularly compounded as the water depth increases since the length of the marine conductor pipe accordingly increases thereby compounding the attendant problems of alignment and assembly. With the increased emphasis on drilling in deeper waters, that is, beyond diver depths and up to a thousand feet or more, the need for a marine conductor pipe which is easy and quick to assemble and reliable in operation is a pressing need in the development of underwater wells, particularly those wells in which two or more strings are employed.

SUMMARY OF THE INVENTION In view of the aforementioned problems, it is a primary object of the present invention to provide a marine conductor pipe apparatus comprised of a plurality of pipe joints or sections which are readily coupled by means of a stab-type connection and which include a plurality of tubing string sections mounted side-by-side; said tubing strings being joined with tubing string sections in an adjacent marine conductor pipe joint when the joints are made up so as to form a composite marine conductor pipe with the pipe strings iextending therethrough and said marine conductor pipe having means on the lower end thereof for connecting the pipe to a production wellhead and for securing the tubing strings in fiuidtight relationship with passageways formed in the production wellhead which in turn communicate with tubing strings extending into the well casing.

Another object of the invention is to providean apparatus of the subject type in which the side-'by-side tubing string sections in each marine conductor pipe joint may be closely associated by longitudinally offsettting or staggering the tubing string sections each to the other.

Still another object of the invention is to provide the subject apparatus with means for removably latching said tubing string sections in said marine conductor pipe joints so that the tubing string section can be removed for re-- pair or replacement.

These and other objects of this invention will become apparent from a reading of the detailed description of the invention.

In accordance with these objects, the marine conductor pipe according to this invention is made up of a plurality of pipe joints or sections having an outer casing containing tubing string sections mounted side-by-side and secured within the casings. The pipe is made up at a surface vessel or installation by stabbing the joints together in end-to-end relationship. Each joint incorporates stab-type connector means at each end thereof and the tubing strings similarly carry stab-type connector means at each end so that when the joints are made up the tubing strings are also connected in fiuidtight relationship to form a composite marine conductor pipe. When the marine conductor pipe is lowered into position by adding successive pipe joints to the top of the marine conductor pipe, the lowermost marine conductor pipe joint, which is provided with coupling means on its lower end, is stabbed onto the top of a production wellhead to secure the tubing strings carried therein in fluid communication with passageways formed in the production wellhead that in turn communicate with tubing strings in the well casing. In addition, the tubing string sections may be axially staggered with respect to each other to permit closer side-by-side spacing of the tubing string sections and further, the sections are preferably removably secured in the casings by releaseable latching means so that the sections may be removed for repair or replacement.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a diagrammatic view taken in longituinal projection 10 illustrating a floating vessel posioned over a drilling location wherein a production wellead assembly is positioned on the ocean floor and a iarine conductor pipe extends generally between the 'ellhead assembly and the drilling vessel at the surface, 1st prior to connecting the marine conductor pipe to 1e wellhead;

FIGURE 2 is an enlarged detail View taken in longituinal projection in partial cross section showing the pper portion of the production wellhead assembly and 1e marine conductor pipe connected thereto for illustrave purposes, two internal tubing strings have been aown;

FIGURE 3 is a longitudinal cross-section taken trough one length or joint of the marine conductor pipe; FIGURE 4 is a plan view of the upper end of the larine conductor pipe joint shown in FIGURE 3;

FIGURE 5 is a partial cross-section taken along the ne 55 of FIGURE 4; and,

FIGURE 6 is a partial cross-section taken along the ,ne 66 of FIGURE 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIGURE 1 of the drawing, a floating (or ottom supported) vessel 11 of a type suitable for per- Jrming completion and work-over operations on an nderwater well is illustrated floating on the surface of body of water 12 while positioned over a preselected ell location by suitable vessel positioning means well nown in the art or by means of anchor lines (not shown) xtending to the floor 13 of the body of water. The drill- 1g vessel 11 is equipped with a suitable derrick 16 conaining a power-operated hoist or fall line system 17 for )wering a marine conductor pipe in a manner to be escribed later. The vessel 11 is also provided with suitble auxiliary equipment for performing completion or maintenance operations on the Well once the marine conluctor pipe is in place. Such operations include, for xample, pumping a well tool or instrument into and out f a well or other operations as described in US. Patents ,052,302; 3,090,440 and 3,268,006.

As shown in FIGURE 1 a well 18 has been drilled into formation underlying the floor 13 of the body of water lid is provided with a production wellhead assembly 22 ositioned on the ffoor 13 in communication with the lell. The well is cased in a conventional manner by Jeans of a casing 19 and is further provided, for xample, with dual tubing strings 20 and 21 extending nto the well 18 through the casing 19. The drilling of ne well 18 and the installation of the production wellhead 2 may be accomplished by suitable operations well Lnown in the art which do not form a part of this invenion. Running from the production wellhead and adapted 3 lie along the floor of a body of water are, for example, wo flowlines 23 and 24 which serve to handle the offtake If oil and/ or gas produced from the well 18. These Howines may extend to a suitable underwater collecting acility or directly to storage facilities located on shore.

The underwater production wellhead assembly in ludes a base member 25 provided with suitable guide tests or columns 26 and 27 having attached guidelines 28 and 29, respectively, extending upwardly to the vessel .1 at the water surface. A marine conductor pipe, indi- :ated generally by the numeral 30, is shown in FIGURE being lowered down the guidelines 28-and 29 by means If radially-extending guide arms 31 and 32 which are .ttached to the lower end of the marine conductor pipe. The guide arms 31 and 32 include a guideline receiving Iortion 33 and 34, respectively, which surround the ;uidelines and are freely movable therealong.

It will be noted at this point that the marine conductor npe 30 is comprised of a plurality of pipe lengths or joints 35 which are joined end-to-end to form the marine conductor pipe 30. Located on the vessel is a rotary table, 10 or other suitable pipe-holding device which is employed when lowering the marine conductor pipe. As shown, the rotary table 10 is used to temporarily hold the marine conductor pipe while an additional pipe joint or line 35 is added onto the upper end of the string. After the length is added, the assembled marine conductor pipe is lowered by means of the fall line system 17 and the newly-added pipe is then held by the rotary table. Thus, successive lengths are added to the marine conductor pipe until the lower end reaches the production wellhead assembly 22 where it is connected in a manner to be described.

The pipe joints 35 may vary in length but are typically in the order of 40 feet long to permit ease of assembly and disassembly. At the lower end of the marine conductor pipe 30 is a short pipe section or sub 36 which is shown in greater detail in FIGURE 2.

Referring now to FIGURE 2, the lower end of the marine conductor pipe 30 is illustrated in its final position connected to the production Wellhead assembly 22. The production wellhead assembly 22 includes at its upper end a short connector pipe 37 of the type shown in US. Patent No. 3,102,591 having a pair of passageways 38 and 39 formed therein and which communicate through suitable passages (not shown) formed in the production wellhead assembly 22 with the tubing strings 20 and 21 located in the well 18. At the lower end of the sub 36 is an enlarged female connector end 40 adapted to receive the connector pipe 37 on the production wellhead assembly 22. This female connector 40 is commonly known in the art as a wellhead connector and may be of any type, e.g., as shown in US. Patent 3,163,224. The female connector end 40 is formed with a flared mouth portion 41 which serves to axially align the female connector end 40 with the connector pipe 37. The female wellhead connector 40 and the connector pipe 37 may also be provided with orienting means to assure accurate rotary alignment between the two parts of this function may be performed solely by the cooperation of the guide arms 31 and 32, guidelines 28 and 29, and the guide posts 26 and 27. In any event the orienting means must include one portion carried by the production wellhead assembly and one portion carried by the conductor pipe and may be of the type, for example, as described in US. patent to Haeber 3,189,098.

FIGURE 5 is a cross-sectional view illustrating one of the pipe joints 35 that make up the marine conductor pipe. The joint 35 includes an outer tubular casing 42 terminating in a female connector housing 43 at the upper end thereof and a male connector housing 44 at the lower end. The upper end of sub 36 is also provided with a female connector housing 69 which is identical to the female connector housing 43 of the joint 35. The pipe joints are arranged during assembly so that the male connector housing 44 of one pipe joint mates with a female housing connector of an adjacent joint. The male connector housing includes an annular recess or groove 45 formed about its outer periphery for receiving locking dogs 46 carried by the female connector housing 43. The dogs 46 are received in apertures or recesses 46a formed in the wall of the female housing 43 and are adapted to be horizontally displaced. Suitable actuating means for extending the dogs 46 into locking engagement with the groove or recess 45 of another pipe joint are carried on the outer periphery of the female connector housing 43. These means comprise an upper ring 47 and a lower ring 48 adapted to permit limited longitudinal sliding movement along the housing. The rings are normally biased apart by means of compression coil springs 49 carried in recesses 49a formed in the rings 47 and 48 (see FIGURES 4 and 5). A plurality of circumferentially-spaced actuating means in the form of bolts 50 extend through the ring 47 and threadably engage the ring 48 so that axial rotation of the bolts 50 serves to move the rings toward each other or away from each other depending on the direction the bolts are turned. Each ring is cut away or relieved in the vicinity of the locking dogs 46 to form a cam surface 47a on ring 47 and a cam surface 48a on ring 48 so that when the rings are in the expanded condition, that is, when they are separated, the dogs 46 may be retracted to permit entry into housing 43 of a male connector housing 44 from an adjacent pipe joint. After the male connector housing 44 is inserted in the female connector housing 43, the actuating bolts 50 are rotated to bring the rings 47 and 48 together as shown in FIGURE 3 so that cam surfaces 47a and 48a force the locking dogs 46 inwardly into the annular recess 45 formed in the male connector housing 44 of the adjacent pipe joint.

Suitable locking means may be carried by the upper end of the female connector housing for preventing the actuating bolts 50 from inadvertently turning. These means may take any suitable form, for example, a locking plate 51 adapted to engage the head of the actuating bolts 50 to prevent rotation thereof as shown in FIGURE 4. The plates 51 may be carried by a shaft 52 which is biased by spring 53 to force the plate 51 into contact with the head of the actuating bolt 50 (see FIGURE 6). Thus, when it is desired to turn the actuating bolt 50, the locking plate 51 is lifted against the action of spring 53 and rotated out of alignment with the head of the actuating bolt so that the bolt may then be turned. Subsequently, the ring 51 is returned to the position shown in FIG- URE 4 to thus lock the actuating bolt. In addition, suitable elastomeric sealing rings 54 may be carried on the internal wall of the female connector housing 43 to assure a fiuidtight seal between the connector pipe joints thereby preventing the ingress of sea water into the casing 42.

Carried within each joint 35 and including therewith are two or more small-diameter tubing string segments 55 and 56 positioned side-by-side. Since the tubing string segments are slightly shorter than the casing 42 they are protected from damage during handling and assembly on the vassel 11. The upper end of the tubing string segment 55 is provided with a female stab-type connector portion 57 having an internal diameter approximately equal to the external diameter of a mating end of a tubing string section of an adjacent pipe point. Carried internally of the connector portion 57 is a cylindrical sealing member 58 of plastic, rubber or other suitable material. The upper end of the tubing string segment 56 is similarly formed with a female stab-type connector 59 having a cylindrical sealing member 60 for connecting with a tubing string section of an adjacent pipe joint. The lower end of the pipe string sections 55 and 56 form male stab-type connectors 61 and 62, respectively, for mating with the female portions of tubing string sections in an adjacent pipe joint.

As shown, the tubing strings 55 and 56 are axially staggered with respect to each other so that the female mating portions 57 and 59 will clear each other and allow minimum spacing between the tubing strings. However, such an arrangement is not essential to the subject invention and if desired the tubing strings may be positioned side-by-side with no axial offset without departing from the scope of the invention. In addition, it is to be noted that the tubing strings are preferably removably secured to the outer casing of the pipe joint in order to permit replacement or repair of a tubing string segment. Suitable apertured locating plates 66 and 67 may be employed at spaced intervals along the tubing strings 55 and 56 to locate and maintain the spacing between the tubing strings. Snap rings 68, as shown at the intersection of tubing string 55 and the locating plate 67, serve to releasably secure the locating plate to the tubing string 55. Other means for spacing the tubing strings may also be used, for example, the strings may be fitted with spiders which contact the interior of the casing 42. As shown in 6 FIGURE 3, the tubing strings may have a ring 63 or any suitable member attached thereto which is formed with an annular groove 64 about the outer periphery for receiving set screws threadably carried in the female connector housing 43. Thus, it will be seen that the set screws 65 when threaded inwardly as shown in FIGURE 3 serve to fixedly secure and lock the tubing strings and 56 in place within the interior of the tubing string 35. If it is desired to replace a tubing string, e.g., to repair it or change the size, set screws are released and the entire assembly of tubing strings 55 and 56 and locating plates 66 and 67 are removed. Thereafter, the tubing strings can be diassembled from the locating plates by releasing snap rings 68. It will be apparent, however, to one skilled in the art that other means may be employed for removably securing the tubing strings or if desired they may be fixedly secured.

Although each pipe joint and tubing string segment has been disclosed with a female upper end and a male lower end, it will be readily apparent that any of the ends may be reversed so long as consistently done throughout the length of the marine conductor pipe or, if desired, the pipe joints may be inverted during assembly.

The marine conductor pipe 30 is made up and connected to the production wellhead assembly 22 as follows. The wellhead connector 40 and short sub 36 which form the lowermost end of the marine conductor pipe are guided by means of guide arms 31 and 32 down the guidelines 28 and 29 as successive pipe joints 35 are added at the vessel 11. As each joint is added the entire assembly is lowered by means of the hoist or fall line system 17 in the derrick 16 a distance equal to the length of the newly-added pipe joint. The assembly is then held by slips (not shown) in the rotary table 10 or other suitable pipe holding means while the next pipe joint is added. It will be apparent that each pipe joint 35 is assembled to the next successive pipe joint by stabbing the male connector housing 44 into a mating female connector housing 43. This action simultaneously affects connection of the tubing string segments 55 and 56 by stabbing the male ends 61 and 62 into the female ends 57 and 59, respectively. After the pipe joints are mated, the actuating bolts 50 are rotated to draw the locking rings 47 and 48 together. As the rings 47 and 48 come together, cam surfaces 47a and 48a engage the dogs 46 and drive them inwardly into groove 45 to thereby lock the pipe joints together. Thus, it will be seen that as the pipe joints are assembled a composite marine conductor pipe is formed having two or more continuous tubing strings extending therethrough. When the marine conductor pipe is finally assembled and lowered onto the production wellhead assembly 22, the female wellhead connector 40 at the lower end of the sub 36 is stabbed and latches onto the connector pipe 37 carried by the production wellhead assembly 22 as shown in FIGURE 2. The tubing string segments 36a and 36b carried in the sub 36 mate with and stab into the passageways 38 and 39 formed in connector pipe 37 which, as described above, communicate with the tubing strings 20 and 21 extending into the well 1-8. Thus assembled, the tubing strings of marine conductor pipe 30 provide two or more passageways from the vessel 11 to the well 18 suitable for pumping workover tools into and out of the .well or for other operations. It will be seen that once the completion or workover operations are finished, the marine conductor pipe can be removed to the surface and disassembled by reversing the assembly procedure described above.

We claim as our invention:

1. An apparatus for conducting well completion and maintenance operations on an underwater well, said apparatus comprising:

an underwater production wellhead assembly positioned adjacent said well and having vertical fluid passageway means extending therethrough in communication with said well;

a marine conductor pipe extending substantially vertically between said wellhead assembly and the water surface;

a surface vessel positionable above said wellhead assembly;

support means carried by said vessel for contacting and supporting the upper end of said conductor pipe;

said marine conductor pipe being formed of a plurality of pipe joints, each joint comprising:

a large diameter tubular casing;

small diameter tubing string means carried within said casing and extending longitudinally therethrough;

first stab-type connector means carried by the ends of said casing for connecting said joints in endto-end relationship whereby said casings define a sealed periphery along the length of the marine conductor pipe;

second stab-type connector means carried by the ends of said tubing string means for connecting the tubular string means in each casing in fluidtight end-to-end relationship within the sealed periphery defined by said casings when said joints are connected; and

coupling means carried by the lower end of said marine conductor pipe for securing said tubing string means to saidwellhead in fluid communication with the fluid passageway means in said wellhead.

2. An apparatus as defined in claim 1 wherein said assageway means comprise two or more adjacent passigeways and said adjacent tubing string means comprise W or more tubing strings, each in alignment with one of aid passageways.

3. An apparatus as defined in claim 2 wherein said ubing strings are axially displaced one to the other.

4. An apparatus as defined in claim 3 including:

horizontally extendible locking means carried by one end of said casing;

recess means formed in the other end of said casing for receiving cooperating locking means; and

actuating means carried by said one end for extending said locking means into engagement with said recess means,

whereby said one end of a casing of one joint is connectible to said other end of a shell of another joint 5. In a marine conductor pipe extending between a vessel positioned on the surface of a body of water and a production wellhead on the floor of said body of water, said wellhead having two or more fluid passageways extending vertically therethrough in communication with the well, said marine conductor pipe comprising:

a plurality of pipe joints connected in end-to-end rela tionship, each joint comprising:

a large diameter tubular casing;

tubing string means carried within said casing and extending longitudinally substantially the length thereof;

first stab-type connector means carried by the ends of said casing for connecting said casings in end-to-end relationship;

second stab-type connector means carried by the ends of said tubing string means for connecting the tubing string means carried in each casing in fluidtight end-to-end relationship; and

coupling means carried by the lower end of said marine conductor pipe for securing said tubing string means to said wellhead in fluid communication with the fluid passageway means in said wellhead.

6. An apparatus as defined in claim 5 wherein said tubing string means comprise, two or more side-by-side tubing strings each of which is in communication with corresponding fluid passageways in said wellhead.

7. An apparatus as defined in claim 6 wherein the tubing strings carried in each of said pipe joints are axially staggered one to the other.

8. An apparatus as defined in claim 7 including:

latching means carried by said casing and adapted to engage said tubing strings for removably securing said tubing strings in said casing.

References Cited UNITED STATES PATENTS 3,064,735 11/1962 Bauer et a1. 166.6 3,189,098 6/1965 Haeber 7 X 3,332,484 7/1967 Watkins 166.6 3,354,951 11/1967 Savage et al 166-.6 3,355,899 12/1967 Koonce et a1. 1757 X CHARLES E. OCON-NELL, Primary Examiner R. E. FAVREAU, Assistant Examiner 

